Low saturable intensity, large TPA coefficient and the absorption cross-section demonstrate that tellurene is an advanced broadband nonlinear absorption material and has potential applications in the nonlinear optics field, especially in the infrared band.

A compact saturable absorber mirror (SAM), based on multilayered black phosphorus (BP) nanoplatelets, was fabricated and successfully used as an efficient saturable absorber (SA) in a passively Qswitched Tm:YAP laser at 1.9 μm. With the BP SAM, Q-switched pulses with a duration of 181 ns and an average output power of 3.1 W were generated at a pulse repetition rate of 81 kHz. This resulted in a pulse energy of 39.5 μJ which, to the best of our knowledge, is the record among the reports on BP SA-based Q-switched lasers. In addition, the simultaneous dual-wavelength Q-switched operation at both 1969 and 1979 nm has been observed. The results indicate the promising potential of multilayered BP nanoplatelets as SAs for achieving efficient pulsed lasers at around 2 μm.

In this study, β-antimonene nanosheets were exfoliated using liquid-phase exfoliation assisted by sonication. The nonlinear absorption properties of β-antimonene nanosheets were systemically investigated. Our results demonstrate that antimonene is a promising candidate as a saturable absorber and an optical limiting material.

Various two-dimensional (2D) materials show unique optical properties and excellent performance in acting as saturable absorber (SA) for demonstrating all-fiber ultra-fast lasers. Tellurene, as a new-fashioned few-layer 2D monoelemental material, was designed as an excellent saturable absorber to achieve Q-switched and mode-locked operations within erbium-doped fiber (EDF) lasers in our experiment. High-quality tellurene-based SA with a modulation depth of 0.97% was obtained by blending few-layer tellurene nanosheet solution prepared by liquid phase exfoliation method and the polyvinyl alcohol (PVA) solution. Inserting the SA into the EDF laser cavity by sandwiching the tellurene-PVA film between two fiber ferrules, either the passively Q-switched or the passively mode-locked operations can be obtained. The repetition rate varies from 15.92 to 47.61 kHz, and the pulse duration decreases from 8.915 to 5.196 µs in the passively Q-switched operation. To the best of our knowledge, this is the first demonstration focusing on the modulation application of tellurene in designing Q-switched pulsed laser operations. Additionally, mode-locked operations were also achieved by adjusting the polarization state. The obtained results fully indicate that tellurene can be developed as an efficient SA for pulsed fiber lasers.

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